Marcela Morvová

Removal of cyclohexanone in transition electric discharges at atmospheric pressure

Two new types of streamer-induced electric discharges operating in a non-uniform electric field in air at atmospheric pressure were applied to the removal of volatile organic compounds (VOCs). The first type is a pulseless dc discharge with physical properties corresponding to the glow discharge. The second, also supplied by a dc high voltage of both polarities, is a spontaneously pulsing discharge operating in the regime of the streamer-to-spark transition, the spark phase being too short to reach local thermodynamic equilibrium conditions. Both discharges are able to generate a non-thermal plasma, as resolved from their rotational and vibrational temperatures. The influences of these discharges on the removal of cyclohexanone at various gas flow rates and concentrations (600-6000 ppm) were compared. The removal efficiencies achieved were about 50-60%, and the energy costs were 16-100 eV/molecule at various energy densities. Special conditions where CO2 and other gaseous products are minor and dominant products appear in the condensed phase can be obtained, especially in the spontaneously pulsing transition discharge. We explain some plasmochemical processes induced by the discharges by considering heterogeneous effects of the copper electrode surface. The role of active nitrogen and the formation of the NCO radical are probably key factors leading to the formation of the condensation product based on amino acids, here produced for the first time from VOCs, as well as in the overall energy cycle resulting in low energy costs of the process. The small pilot-scale reactor based on the spontaneously pulsing transition discharge has been successfully applied to the removal of cyclohexanone in the mixture with other VOCs with no noxious gas output. This validates the possibility of the application of such a type of reactor for larger scales.

Dc corona discharges in -air and CO-air mixtures for various electrode materials

Positive and negative dc corona discharges in CO-air and -air mixtures were applied. Natural humid air was used. The step by step development with time of the formation of gas products after the action of the corona discharge was measured in situ. The discharge tube was situated in an IR gas cell. The IR absorption spectra were scanned from the area of the inter-electrode distance in successive time steps of the action of the discharge (about 1 min). Measurements were performed for three combinations of electrode materials, namely Mo-stainless steel, Mo-brass and Cu-brass. Reflection IR absorption spectra from the surfaces of the electrodes used were scanned after the action of the discharge. The influence of the electrode material on the development with time of the reaction products was observed. Polymer-metal complexes with possible catalytic activity are formed on the surfaces of electrodes. From measurements it resulted that the discharge processes consist of simultaneously acting volume processes of plasmochemical nature (probably initiated by electrons) and electrocatalytic surface processes on electrodes (probably initiated by photons).

Plasma Technologies for Reducing CO2 Emissions From Combustion Exhaust with Toxic Admixtures to Utilisable Products

The method reported here provides a contribution to CO2 and combustion exhaust utilisation. A multifunctional system for gas removal was tested on various sources of exhaust (internal combustion engine, brown coal boiler, bituminous pulverised coal boiler, gas boiler, glass oven, VOC sources) in full-scale or by-pass gas flow volumes.A spontaneously-pulsing, direct-current electric discharge operating in a corona geometry was used. The discharge has strongly shining channels migrating quickly along the stressed electrode. The synergetic effect of electric discharge and heterogeneous catalysis on the organometallic part of the product formed on the non-stressed electrode was responsible for the specific character of the products. The final product of the process is a powder with a fractal structure on the microscopic level with low specific mass and insoluble in water. The main component (95%) of the solid product is an amorphous condensate of amino acids with about 5% of organometallic compound with catalytic properties. The product was analysed using IR absorption spectrometry, microscopic photography, HPLC and thermogravimetry. The following amino acids were observed in the final product: alanine, serine, glycine, aspartic acid, lysine, arginine, methionine, histidine.

Effects of chronic kidney disease on blood cells membrane properties

Chronic kidney disease (CKD) is progressive loss of renal function associated among others with increased intracellular calcium concentration. The purpose of this study was to identify the effects of CKD on cell membrane properties such as human red blood cell Ca(2+) ATPase activity, lymphocyte plasma membrane P2X(7) receptor expression and function. This could help us in elucidating the origin of increased calcium concentration in blood cells. We found out Ca(2+) ATPase activity is decreased in early stage CKD patients resulting in altered calcium removal from cytoplasm. By means of flow cytometry we assessed that P2X(7) receptor expression on lymphocyte membrane is 1.5 fold increased for CKD patients. Moreover, we detected an increased uptake of ethidium bromide through this receptor in CKD at basal conditions. It means CKD lymphocyte membranes contain more receptors which are more permeable thus allowing increased calcium influx from extracellular milieu. Finally, we can state alterations in blood cell membranes are closely linked to CKD and may be responsible for intracellular calcium accumulation.

Supplementary research of clinoptilolite-rich tuff composites after adsorption trials using the XPS technique

The paper deals with fabrication of carbonized and hydrophobized clinoptilolite-rich tuff using organic carbon rich substances, here particularly starch and waste vegetable residues, which were pyrolytically combusted and covered the external zeolite surface. Hydrophobization of the zeolite external surface was accomplished by octadecylammonium surfactant. Both surface modified clinoptilolite-rich tuffs were tested and compared with each other with regard to removal of organic (phenol) and inorganic (chromate, arsenate) pollutants from aqueous solutions. These elaborated composites with surface adsorbed pollutant species were analysed by X-ray photoelectron spectroscopy (XPS).

Positive DC corona discharge in N2-NO-CO2-O2 mixtures

Positive DC corona discharge in a hemicylindrical discharge reactor was applied to mixtures containing N2, NO, O2, CO2 and H2O, while an NOx chemiluminescence analyzer and an IR spectrometer were used to evaluate the concentration changes and analyze the products of the process in the discharge chamber. The removal efficiency of 89% for NO and the energy cost of 350 eV/molecule were achieved. Special attention was paid to the influence of CO2 on discharge, its character, performance and products of the process. In addition to the main components of the gas mixture (NO, NO2, CO2, CO etc.), other compounds and functional groups (e.g., amides I–III, imides, NCO) have been identified among the products of the process.

Thermochemical aspects of the conversion of the gaseous system CO2-N2-H2O into a solid mixture of amino acids

Conversion of the gaseous mixture CO2(g)+N2(g)+H2O(g) to a solid amino acid condensate in an electric discharge plasma has high efficiency of the energy transfer from the different plasma components into chemical processes. The basic activation process is activation of the N2 metastable electronic state, followed by formation of NCO* and ON-NCO free-radicals and generation of many reactive radicals. These radicals help to overcome the high activation energy of thermal dissociation of N2 to N (950 kJ=9.846 eV).The major product is a statistical polycondensate containing the amino acids: arginine, lysine, histidine, methionine, glycine, alanine, serine and aspartic acid. This information was obtained by comparing the IR spectra of the products with reference IR absorption spectra of pure components. Identification of the individual amino acids in the solid product was performed by HPLC, when samples were dissolved using 6 M HCl applied at 100°C for 24 h. Properties of the condensate were estimated using thermogravimetric analysis. Small amounts of oxamidato complexes and oligo pyrrole structures are formed on the electrode surface giving the surface catalytic properties. The gas cleaning process has practical applicability (production of useful fertilizers, reduction of the CO2 concentration in the atmosphere) and may also contribute to explanation of the origin of life on Earth.

The influence of water vapour and temperature on depletion of carbon monoxide in D.C. corona discharge

The plasmochemical and/or electrocatalytical reactions of carbon monoxide with water vapour were studied. Dc corona discharge of both polarities at room temperature and temperatures enhanced up to 70°C was applied at pressures close to atmospheric.The reaction products were analysed by IR absorption spectrometry. The main products in the gas phase were CO2 and CH4. The reactions are influenced by the formation of a catalytically active surface layer on electrodes. The composition of this layer depends on the polarity of electrode.

The Impact of Vitamin D3 Supplementation on Mechanisms of Cell Calcium Signaling in Chronic Kidney Disease.

Intracellular calcium concentration in peripheral blood mononuclear cells (PBMCs) of patients with chronic kidney disease (CKD) is significantly increased, and the regulatory mechanisms maintaining cellular calcium homeostasis are impaired. The purpose of this study was to examine the effect of vitamin D3 on predominant regulatory mechanisms of cell calcium homeostasis. The study involved 16 CKD stages 2-3 patients with vitamin D deficiency treated with cholecalciferol 7000–14000 IU/week for 6 months. The regulatory mechanisms of calcium signaling were studied in PBMCs and red blood cells. After vitamin D3 supplementation, serum concentration of 25(OH)D3 increased (P < 0.001) and [Ca2+]i decreased (P < 0.001). The differences in [Ca2+]i were inversely related to differences in 25(OH)D3 concentration (P < 0.01). Vitamin D3 supplementation decreased the calcium entry through calcium release activated calcium (CRAC) channels and purinergic P2X7 channels. The function of P2X7 receptors was changed in comparison with their baseline status, and the expression of these receptors was reduced. There was no effect of vitamin D3 on P2X7 pores and activity of plasma membrane Ca2+-ATPases. Vitamin D3 supplementation had a beneficial effect on [Ca2+]i decreasing calcium entry via CRAC and P2X7 channels and reducing P2X7 receptors expression.

Deletion of the PDR16 gene influences the plasma membrane properties of the yeast Kluyveromyces lactis.

The plasma membrane is the first line of cell defense against changes in external environment, thus its integrity and functionality are of utmost importance. The plasma membrane properties depend on both its protein and lipid composition. The PDR16 gene is involved in the control of Kluyveromyces lactis susceptibility to drugs and alkali metal cations. It encodes the homologue of the major K. lactis phosphatidylinositol transfer protein Sec14p. Sec14p participates in protein secretion, regulation of lipid synthesis, and turnover in vivo. We report here that the plasma membrane of the Klpdr16Δ mutant is hyperpolarized and its fluidity is lower than that of the parental strain. In addition, protoplasts prepared from the Klpdr16Δ cells display decreased stability when subjected to hypo-osmotic conditions. These changes in membrane properties lead to an accumulation of radiolabeled fluconazole and lithium cations inside mutant cells. Our results point to the fact that the PDR16 gene of K. lactis (KlPDR16) influences the plasma membrane properties in K. lactis that lead to subsequent changes in susceptibility to a broad range of xenobiotics.